A. Field of the Invention
The present invention relates to a resin composition capable of yielding a cured resin material exhibiting improved heat resistance and a higher glass transition temperature.
B. Description of the Related Art
In recent years, IGBTs (insulated-gate bipolar transistors), MOSFETs (metal oxide semiconductor field-effect transistors) and other power modules capable of operating at large capacities in high-voltage environments have been used widely in consumer appliances and industrial machines. In some of these various modules using semiconductor elements (hereunder called “semiconductor modules”), the heat generated by the mounted semiconductor element can reach high temperatures. This can occur when the semiconductor element operates at a high power level, when the circuits in the semiconductor element are highly integrated, or when the circuits have a high operating frequency. In such cases, the insulating sealing resin in the semiconductor module must have a glass transition temperature (Tg) equal to or greater than the exothermic temperature.
To impart heat resistance to cured epoxy resin materials used as insulating sealing resins, the molecular structures of conventional epoxy resins have been selected, and crosslinking densities have been increased in an effort to increase the Tg and improve the heat resistance of the cured material. However, methods of improving heat resistance by altering the molecular structure of the epoxy resin or increasing the crosslinking density may adversely affect the viscosity characteristics, hygroscopicity and other essential properties of insulating sealing resins.
A resin composition is also known comprising silica fine particles, a bifunctional epoxy resin, a polyfunctional epoxy resin and an amine curing agent as essential components, which is an epoxy resin composition for a fiber reinforced composite providing high mechanical strength in high-temperature environments (Japanese Patent Application Publication No. 2009-292866). However, the problem is that the desired physical characteristics of the fiber-reinforced composite are obtained when the resin composition is impregnated in reinforcing fibers and then cured, and in this configuration it could not be used as an insulating sealing resin composition for sealing semiconductor elements and other electronic components.
Resins such as these that have insulating properties are also widely used for insulation and internal protection in fuel cells, photovoltaic cells and other electrical components and products, which are devices in which the generated heat may reach high temperatures, and a high glass transition temperature is also desirable for such applications.
The present invention is directed to overcoming or at least reducing the effects of one or more of the problems set forth above.